Patient safety in orthodontic care: a scoping literature review with proposal for terminology and future research agenda

Background Knowledge about patient safety in orthodontics is scarce. Lack of standardisation and a common terminology hinders research and limits our understanding of the discipline. This study aims to 1) summarise current knowledge about patient safety incidents (PSI) in orthodontic care by conducting a systematic literature search, 2) propose a new standardisation of PSI terminology and 3) propose a future research agenda on patient safety in the field of orthodontics. Methods A systematic literature search was performed in the main online sources of PubMed, Web of Science, Scopus and OpenGrey from their inception to 1 July 2023. Inclusion criteria were based on the World Health Organization´s (WHO) research cycle on patient safety. Studies providing information about the cycle’s steps related to orthodontics were included. Study selection and data extraction were performed by two of the authors. Results A total of 3,923 articles were retrieved. After review of titles and abstracts, 41 articles were selected for full-text review and 25 articles were eligible for inclusion. Seven provided information on the WHO’s research cycle step 1 (“measuring harm”), twenty-one on “understanding causes” (step 2) and twelve on “identifying solutions” (step 3). No study provided information on Steps 4 and 5 (“evaluating impact” or “translating evidence into safer care”). Conclusion Current evidence on patient safety in orthodontics is scarce due to a lack of standardised reporting and probably also under-reporting of PSIs. Current literature on orthodontic patient safety deals primarily with “measuring harms” and “understanding causes of patient safety”, whereas less attention has been devoted to initiatives “identifying solutions”, “evaluating impact” and “translating evidence into safer care”. The present project holds a proposal for a new categorisation, terminology and future research agenda that may serve as a framework to support future research and clinical initiatives to improve patient safety in orthodontic care. Registration PROSPERO (CRD42022371982). Supplementary Information The online version contains supplementary material available at 10.1186/s12903-024-04375-7.


Introduction
For decades, patient safety has been recognised as a healthcare discipline.However, the awareness-raising publication of "To Err Is Human" by the Institute of Medicine Committee on Quality of Health Care in the US drew considerable attention to this important aspect of healthcare [1,2].In this publication, experts estimated that in the US in any given year as many as 98,000 people die from medical errors that occur in hospitals [1].The definition of patient safety by the World Health Organization (WHO) from 2009 is: "the freedom for a patient from unnecessary harm or potential harm related to healthcare" [2].Similarly, in their report, Kohn et al. recognised safety as "freedom from accidental injury" [1].In this context, a patient safety incident (PSI) is an event or circumstance that could have resulted or did result in unnecessary harm to a patient [2].
Patient safety is a crucial aspect of healthcare that seeks to minimise preventable harm, accidents, complications and adverse events (AEs).AEs are defined as injuries resulting from poor management practices that could have been prevented but are not attributed to an underlying disease process [2,3].The WHO classifies certain AEs as "never events", which are serious incidents that should not occur given the presence of strong systemic safety measures [4].Never events can have a profound impact on patients, and their prevention is a key objective of healthcare organisations.In this context, patient safety aims to limit the impact of AEs adverse events and promote the avoidance of preventable harm.
Patient safety is a priority from the patient's perspective, and for care providers it falls in line with the Hippocratic Oath ("primum non nocere"), which is an important element of modern healthcare.Patient safety initiatives analyse characteristics and features of healthcare systems that may lead to the occurrence of AEs.These features are latent risks that may be of any nature from a soft tissue laceration or a loose wire to inhalation of an orthodontic appliance [5].Throughout most healthcare treatment courses, multiple latent risks exist and this makes patient safety multifactorial and complex.When an AE occurs, patient safety does not aim to punish but rather to investigate how and why the protective barriers failed [6,7].
Improving the quality of care is a road that passes through patient safety.Additionally, patient safety has additional psychosocial and financial benefits.Dealing with the consequences of an adverse event has an economic cost to the practitioner, the patient and society.By improving patient safety, dental practitioners increase their quality of care, which is associated with safer and better treatment outcomes [8][9][10].In addition, it affords increased legal security by minimising the risk of legal claims [6].
Knowledge about patient safety in dental care and orthodontics in particular is scarce.The absence of patient safety guidelines in orthodontics is a major concern.This issue is further complicated by the absence of standardized terminology in the field, challenging the development of consistent safety protocols.Additionally, there is a noticeable lack of research and publications in this area, which hinders progress in developing effective, evidence-based strategies to ensure patient safety in orthodontic care [11].Therefore, an urgent need exists for studies in the field of orthodontics in particular [2,3,12].Among others, the lack of a common language among orthodontic caregivers ultimately hinders research and limits our understanding of the discipline [13,14].The aims of this study were to 1) summarise current knowledge about PSIs in orthodontic care by performing a systematic literature search; 2) propose a new standardisation of PSI terminology; 3) propose a research agenda on patient safety in the field of orthodontics that may serve to further develop and provide direction for future research on the subject.

Protocol and registration
Prior to the initiation of the project, the study protocol was registered with PROSPERO (reg.no.CRD42022371982).No ethical approval was deemed necessary.

Search strategy
A systematic literature search was performed in the main online sources of MEDLINE (through PubMed), Web of Science, Scopus as well as the System for Information on Grey Literature in Europe (Open-Grey) from their inception to 1 July 2023.No language limitation was set in the search, and all types of eligible human studies were included.
The inclusion criteria for articles were based on the WHO research cycle on patient safety [15,16].The various steps of the cycle aim to measure harm and identify causes while identifying solutions to improve patient safety.The ultimate goal is to translate evidence into safer care (Fig. 1).Only studies that provided relevant information in at least one of the following categories were eligible for inclusion in this systematic review: Only full-text articles were included.In addition, studies dealing with patient safety from a general dental-care perspective were included only if they were directly relevant to orthodontic care and the WHO research cycle.For example, although studies on oral surgery were excluded, wrong-tooth-extraction studies or articles investigating the light-curing safety on patients were included owing to their relevance to orthodontics.

Data extraction
After removal of duplicates, all results returned from the systematic literature search were initially screened by their title to establish their relevance.The second filtering decided relevance for inclusion based on the content of the abstract.Finally, the third filtering level was applied to the main text, and the remaining studies were then included in the review.All screening was performed independently by one of the authors (NF) and was later re-checked by another author (PS).Any disputes in study selection were addressed and resolved through discussion between the reviewing authors.On all included studies the main outcome/result was recorded.This was studies investigating prevalence ("measuring harm"step 1) or assessing contributing factors ("understanding causes"-step 2).For all studies providing information on the cycle's step 3 ("identifying solutions"), all recommended solutions to prevent harm were also noted.Due to the nature of the data in the included studies, no risk of bias assessment was possible.For the same reason, no quantitative synthesis and meta-analysis was performed.Based on these findings, the intention to conduct a systematic review was revised to a scoping literature review instead [17].

Study selection
A total of 3,923 studies were identified from the systematic search and imported into Excel (Microsoft ® , USA) (PubMed n = 2,049, Web of Science n = 663, Scopus n = 1203 and OpenGrey n = 8).Among the 3,923 articles, 237 were deemed relevant according to the inclusion criteria after screening their titles.Filtering by abstracts, left 41 articles for inclusion after removal of the duplicates.In one case, the full-text of an article was unavailable and it was therefore excluded [18].Three relevant articles found in the reference lists were also added [4,14,19].Finally, 25 studies were included as they were found to provide information within any of the categories of the WHO's research cycle on patient safety related to the orthodontic field (flowchart presented in Fig. 2).

Study characteristics
Study characteristics are shown in Table 1.Nine of the included papers were retrospective studies of AEs studying: eye wear protection and ocular trauma in orthodontic practice [19], clinical evaluation of a locking orthodontic facebow [20], adverse reactions to dental materials [3], case reports of latex allergy [21], wrong tooth extraction claims [4], dental and orthodontic PSIs in a UK register [7] and a Finnish register [8], adverse reactions to dental devices reported at the US Food and Drug Administration [9] and investigation of monomer release from orthodontic adhesives [22].
The remaining sixteen studies reported risk assessments of orthodontic procedures or materials.These included safety assessment of dental radiography [23], bonding of brackets under general anaesthesia [24], orthodontic facebows [10], mini-implants [12,25,26], soft-tissue lasers in orthodontics [13], effect of orthodontic treatment on patients' diet [14], eye safety of curing lights [27], safety of metal fixed appliance during magnetic resonance imaging (MRI) [28], pulp safety of Fig. 1 The World Health Organization's research cycle on patient safety consisting of five steps with the main goal of measuring harm and its causes while identifying solutions and their impact.Ultimately, this evidence should lead to safer care with a set of actions and preventable measures various types of curing lights [29], wrong tooth extraction in orthodontics [30][31][32], orthodontic treatment by identifying orthodontic never events [33] and complications after orthognathic surgery [34].These studies identified risks in orthodontic procedures or materials and proposed solutions to manage and minimise these risks.

Measuring harm
Seven of the studies included provided information in the first category of the WHO's research cycle on patient safety, which is "measuring harm" [4, 7-9, 19, 22, 34].Sims et al. conducted a postal survey on eye protection in the UK and found that ocular injuries were reported in 37.7% of all respondents involving orthodontists, assistants and patients [19].Peleg et al. conducted a rootcause analysis of wrong-tooth extraction in 54 insurance claims in Israel and reported that in two thirds of all claims an identification error was the cause of the incorrect tooth extraction [4].Also, a cross-sectional study on PSIs in the UK found that orthodontic PSIs accounted for 8.9% of all reported dental PSIs in the country [7].Hebballi et al. investigated the frequency and types of AEs associated with dental devices as reported to the Food and Drug Administration and User Facility Device Experience (MAUDE) in the US [9].They reported that orthodontic appliances and accessories accounted for 1% of all AEs involving dental devices.In a similar investigation in hospital and private settings in Finland, Hiivala et al. reported that orthodontic PSIs accounted for 3.6% of all dental PSIs [8].Finally, a multi-centre retrospective review of orthognathic surgeries assessing complications and risk factors studied a population of 674 patients [34].They reported that adverse events were rare (4.3%) with superficial incisional infection being the most common.They also concluded that the setting, the type of surgery as well as the patients' ethnicity were identified as risk factors for some types of complications.

Understanding causes of harm & identifying solutions
Twenty-one of the included studies identified the underlying causes of AEs that caused patient harm (WHO's Category 2 "Understanding the causes") [3, 4, 7, 10, 12-14, 19-21, 23-31, 33, 34].In addition, twelve studies identified possible solutions that may be effective in reducing the occurrence of AEs (WHO's Cycle Category 3 "Identifying solutions") [4, 10, 12, 13, 19-21, 23-25, 31, 32].These solutions included: health and safety  instructions for eye-protection goggles to prevent ocular trauma [19], use of non-latex materials [21], clear instructions with a brief description of the tooth to be extracted addressed to the clinician using two different identification methods to prevent wrong-site extraction and use of a computerised checklist [4,31,32], use of facebows with a locking mechanism and self-releasing head strap to prevent injuries from headgear [10,20], suggestions to improve safety in dental radiography [23], use of rubber dam during bonding of brackets under general anaesthesia [24], recommendations to overcome failures and risks during placement, loading and removal of miniimplants [12,25] and, finally, instructions for safe use of soft-tissue lasers in orthodontics recommending that the clinician obtained appropriate training and certification, use of proper eye wear by all involved parties, obtaining informed consent and providing proper post-operative instructions [13].
None of the included studies provided information on how to evaluate the impact of such solutions or on how to translate evidence into safer care in terms of affordability and acceptability.Data synthesis and meta-analysis was not possible due to the heterogeneity of the different studies and the nature of the data.

Patient safety incidents in orthodontics
To our knowledge, this is the first systematic investigation of patient safety in orthodontics.The lack of evidence in the field manifests in our results.Twenty-five studies were included in this review and these studies were only peripherally related to orthodontics while providing some information based on the WHO's research cycle.This cycle describes a process to identify solutions for enhancing patient safety and reducing patient harm.It consists of five steps representing the natural process for patient-safety initiatives.It seems that dentistry in general and orthodontics in particular have yet to take even the initial steps of the cycle (steps 1 and 2), which are to measure the harm and understand the causes of harm [16].This is evident from the results as the included studies were either reviews of risks associated with specific orthodontic procedures (like mini-implant insertion, soft-tissue laser, facebow use, etc.) or retrospective reviews of AEs peripherally related to orthodontics (incidence of ocular trauma, adverse reactions to materials, etc.).
The results of this review document that current evidence relating to orthodontics is scarce.Without a basic understanding of PSIs and harms we cannot begin to understand the causes and identify solutions that will subsequently translate into safer care for our patients [16].A major limitation to this is a trend towards potential under-reporting of PSIs in our field.In fact, a review of the National Patient Safety Agency (NPSA) database in the UK revealed that orthodontics is among the lowest reporting specialties along with dental surgery and paediatric dentistry [35].A contributing factor in this may be the lesser severity of some PSIs in orthodontics, which may be smaller injuries like soft-tissue laceration from loose wires [16].One way to overcome the underreporting issues may be effective keeping of patient records and clinical notes, which may prove an essential tool in clinical audits and will also underpin the reporting of more AEs [36].Also, the lack of standardisation in terminology and reporting process of AEs makes it challenging if not impossible to summarise and categorise all PSIs in orthodontics, let alone analyse the data in depth.
Additionally, we hypothesise that an underreporting bias may exist between dental specialities.Dental implants are more expensive and dentists and/or patients may therefore report them more often when asking for replacements [9].This leads, e.g., to many more reported PSIs for implants than for burs.Finally, another contributing factor in the lack of evidence on patient safety is the overlap found in some areas within dentistry.This makes it more challenging to precisely measure AEs in only one field.A clear example of this is the AE of wrong-tooth extraction for orthodontic reasons, which may fall in both the orthodontic and surgical category.

Standardisation and terminology
The lack of a standardised terminology and reporting of PSIs in orthodontics seems to hinder any effort to summarise and categorise PSIs, which could be a reasonable first research step to enhance our knowledge in this field.For future work in this field, we therefore suggest that PSIs related to orthodontics may be summarised into two main categories; local and systemic.Categorisation with subcategories and examples are shown in Table 2. Terminology according to the WHO is proposed in Table 3.
Local PSIs refer to any harm on dental tissues (root resorption, white spot lesions, pulp necrosis, caries) and soft tissues.This may be damage to both periodontal and surrounding soft tissues that could have been avoided (gingival recessions, soft tissue lacerations, local allergic reaction/contact dermatitis).In addition, local PSIs include treatment injuries with a negative effect on orofacial function.This may be development of lip catch as a result of orthodontic treatment.Finally, any harm related to any unwanted tooth movement is also included in this category.This may be unwanted tooth movement due to an active retainer.
Systemic PSIs refer to harm at a systemic level.This may be excessive pain and discomfort as a result of the orthodontic treatment due to a defective appliance or even hypersensitivity due to excessive interproximal reduction.In addition, systemic PSIs include potential emotional damage to patients.This may be development of general discomfort/odontophobia/mistrust towards the clinician or the healthcare system or deterioration of the oral health-related quality of life (OHRQoL).Systemic PSIs may be a result of delayed treatment initiation due to delayed/inadequate diagnosis.Finally, harm caused by poor cross-infection control, inhalation of orthodontic parts and extraction of a wrong tooth are also considered systemic PSIs.

Future research agenda
A proposal for a future research agenda in orthodontic patient safety is shown in Table 4.The agenda is intended as inspiration to promote future research and development in patient safety in orthodontics.It should not be considered absolute as topics other than those listed may be of interest for future patient safety initiatives.Two main categories of studies are presented in Table 4: Retrospective or prospective studies dealing with patient safety (26).
Retrospective studies are reactive in nature and focus on the incidence, characteristics and severity of PSIs using an acknowledged methodology such as journal file audit and root cause analysis (RCA) (26,27).They investigate PSIs that have already occurred with the intention of generating knowledge to promote learning and guidance for future patient safety initiatives.RCA allows us to focus on individual PSIs and investigate, through a comprehensive analysis, all the contributing factors that lead to the occurrence of an AE.
Conversely, prospective studies assess potential risks associated with a treatment, appliance or material.The methodology in these studies is failure mode and effects analysis (FMEA) (27,28).This approach is the analysis of a method, treatment, material or procedure by first creating a risk map and then implementing measures to reduce the likelihood or impact of a PSI (27)(28)(29)(30).
Both intrinsic and extrinsic motivation are key factors in the establishment of safer future orthodontic care.Intrinsic motivation is shaped by professional ethics, norms and patient-reported outcomes and expectations [1,37,38].The articles included in our review, however, mainly focused on the extrinsic motivation, which refers to the environment, policies and strategies that we may develop with the ultimate goal of improving patient safety in orthodontics.
In orthodontic patient safety research, a need exists to increase our focus on this aspect and on clinical routines and administrative, organisational and legal contexts.One strategy that may help us move in this direction is to establish excellent records and clinical notes through periodical audits [30].This will help clinicians and/or patients report more AEs in future.Honest exchange of such information between health professionals is a necessary first step and a founding rock for safer care and further research.To achieve this, it is important to establish a non-blame culture with psychological safety and a feeling of partnership, enthusiasm and commitment to improving patient safety in orthodontics [36].
Research on patient safety is more advanced in other parts of healthcare than orthodontics.Even other fields of dentistry have taken steps in this direction with the creation of checklists, i.e. in endodontics, orofacial function and oral surgery [39][40][41][42][43]. Checklists seem to have a positive effect on patient safety [44][45][46].Most of the checklists are adaptations of the WHO's surgical checklist that is now used in a wide range of surgical specialties in medicine [47].Adjusting this to fit our orthodontic needs and implementing it in daily practice may be an important step towards improving safety in orthodontics [48].In the past decade, the WHO has published several guidelines and educational curricula to enhance the level of patient safety in healthcare in general [49,50].These publications may provide a starting point for the spreading of local patient safety initiatives and the introduction of educational and organisational measures to further patient safety.Some orthodontic societies seem to have taken steps towards patient safety, however all societies in different countries need to follow and implement policies for safer care.In its core patient safety is the purpose of audit and clinical governance.Amongst other, research is a vital element in this process.Nevertheless, a limitation in this could be that clinical governance might differ from one country to another.
Traditionally, patient safety was focused on rare types of incidents with a significant degree of harm referred to

Patient safety
Freedom from accidental injury.The avoidance, prevention and amelioration of adverse outcomes or injuries stemming from the processes of healthcare.These events include "errors", "deviations" and "accidents".Safety emerges from the interaction of the components of the system; it does not reside in a person, device or department Patient safety incident An event or circumstance, which could have resulted, or did result in unnecessary harm to a patient Prevention Modification of the system to decrease the probability of the dreaded event arising and to return to an acceptable risk level; any measure aiming at reducing the frequency and the severity of the risk Quality of care Degree to which health services for individuals and populations increase the likelihood of desired health outcomes and are consistent with current professional knowledge

Risk
The likelihood, high or low, that somebody or something will be harmed by a hazard, multiplied by the severity of the potential harm Safe care Safe care involves making evidence-based clinical decisions to maximise the health outcomes of an individual and to minimise the potential for harm Safety culture An integrated pattern of individual and organisational behaviour, based upon shared beliefs and values, that continuously seeks to minimise patient harm that may result from the processes of care delivery

Underlying cause
The systems or process cause that allow for the proximate cause of an event to occur.Underlying causes may involve specialcause variation, common-cause variation, or both as "never events" in the literature [51].However, in recent years, more efforts have been devoted to understanding the frequency and causes of PSIs that we assume occur more frequently than is reported today [51].The perceived threshold determining what is considered a PSI may often be vague; and the border is not absolute, particularly as we come to understand patient safety better.
It is important to emphasize that common side effects (e.g., root resorption) are not considered PSIs as these side effects may also occur when a patient has undergone an optimally performed course of treatment, unless, of course, these side effects were avoidable and appropriate measures had been adopted [52].The extent of such side effects, however, can vary and probably depends on a wide range of factors (force magnitude, treatment duration) [53].Excessive root resorption, however, may be considered a PSI if the risk factors were not assessed before initiating treatment and if precautionary measures were not taken in advance.A step towards safer orthodontics may be to incorporate such "risk maps" routinely in systematic reviews.For example, when a systematic review compares A to B, reporting just which of the two is more efficient or faster may be insufficient.The burden and the risk of harm to the patient should also be reported.This reporting may include anything that may be considered a PSI, from excessive root resorption to increased exposure to radiation, cytotoxicity, effect on patients' OHRQoL, late diagnosis, overtreatment, gingival recessions or bone dehiscence, etc.A cultural change in the way we approach these "side effects" and further patient-centred research will improve patient safety in our field.In addition, in today's rapidly evolving technological landscape, where new advancements outpace research capabilities, emphasizing the safety of orthodontic materials is crucial while treatment decisions need to be patient-centred, based on their perspective [54].

Strengths and limitations
The strengths of this systematic review include an extensive literature search, a predefined protocol, a priori registration with PROSPERO and the adoption of a strict methodology at all study stages [55].Also, the fact that there was no date or language limitation in the search, provided us with data that likely reflect the current understanding and knowledge about PSI in orthodontics.
In addition, the proposed categorisation of PSIs in orthodontics and the future-agenda proposals may spark interest and lead to further research in the field of orthodontic patient safety.Certain limitations need further consideration: mainly the inability to assess precise prevalence of orthodontic PSIs and categorise them accordingly.This inability is due to the poor current evidence and lack of standardisation and terminology and the fact that many PSIs are probably underreported.It can also be due to the fact that patient safety is a topic of increasing complexity, especially with the new risks arising directly from the use of new technologies [51].Also, there is inherent risk of bias due to the nature of the studies included which were mostly retrospective [56].Furthermore, in this study, the final selection of the included studies was consensus-based instead of individually assessing the suitability of the articles during the review process.Finally, despite thorough searching, there could be studies overlooked during the

Conclusion
Current evidence on patient safety in orthodontics is scarce due to a lack of standardisation and potential under-reporting of PSIs.The current literature on orthodontic patient safety deals mostly with "measuring harms" and "understanding causes of patient safety", whereas less attention has been devoted to initiatives "identifying solutions", "evaluating impact" and "translating evidence into safer care".The present project presents proposals for a new categorisation, terminology and a future research agenda that may serve as a framework to support future research and clinical initiatives to improve patient safety in orthodontic care.

Fig. 2
Fig. 2 PRISMA flowchart diagram of the systematic literature search and inclusion procedure

Table 1
Included studies with main information and study characteristics (design, country), main outcomes and information provided based on the WHO's research cycle on patient safety

Table 2
Orthodontic patient safety incidents summarised as the two main categories of local and systemic, with examples.Local patient safety issues (PSIs) are related to harm in the dental (or surrounding) tissues, orofacial function and unwanted tooth movement.Systemic PSIs refer to pain and discomfort, emotional harm or other as part of an orthodontic treatment.Harms related to orthodontic care may fall into more than one of the categories

Table 3
Terminology proposed in orthodontic patient safety future research inspired by the WHO's Conceptual Framework for the International Classification for Patient Safety Final Technical Report

Table 4
Aspects and examples of future initiatives and research.Orthodontic patient safety research agenda should follow the WHO's research cycle.The table does not represent all relevant aspects for future research.Rather, it highlights important aspects to elucidate among many other relevant aspects Translating evidence into safer care Implement PS in the curriculum of dental schools/post-graduate orthodontic programs Apply evidence from other medical fields on how to promote safe patient care Encourage national and international orthodontic societies to play a vital role in the promotion of orthodontic care process, possibly originating from databases not encompassed in the search.